1. Field of the Invention
The present invention relates to a lens holder for use with a lens driving device based on a voice coil motor system, wherein the lens holder has a predetermined length along a vertical direction an optical axis direction and a coil is wound around an outer circumference thereof. The present invention also relates to a lens driving device, a camera device and an electronic device in which the lens holder is mounted.
2. Description of the Relevant Art
In the conventional relevant art field, the lens driving device based on the voice coil motor system has been employed in the autofocus camera or camera-equipped electronic device. This lens driving device allows the lens position to be adjusted so that it can be aligned with the optical axis direction, thereby providing the focusing or zooming function.
In the lens driving device based on the voice coil motor system, it is general that the lens driving device having the structure shown in FIG. 9(a) has been employed. The lens driving device 1 that is illustrated as a typical example in FIG. 9(a) includes a frame 2, a yoke 3, a lens holder 4, a coil 5, a magnet 6, a front side spring 7, a rear side spring 8, and a base 9.
The yoke 3 is supported on the base 9, and the magnet 6 is mounted to the yoke 3. The lens (not shown) is supported by the lens holder 4 having a predetermined length along the vertical direction. On the outer circumference of the lens holder 4, there is the coil 5 which is wound around it such that the coil 5 can face opposite to the before described magnet 6.
The lens holder 4 is held securely between the upper side of the optical axis direction and the lower side of the optical axis direction by the front side spring 7 and the rear side spring 8 so that the lens holder 4 can be aligned with the optical axis direction (the vertical direction). In this way, the lens holder 4 is supported so that it can be moved along the vertical direction (the optical axis direction).
A thrust is produced by controlling the current that is applied across the coil 5. This thrust forces the lens holder 4 and the lens supported thereon to be moved. In this way, the lens (not shown) can be moved up to the position where the thrust is balanced with the respective restoring forces provided by the front side spring 7 and the rear side spring 8. The focusing or zooming function may thus be provided.
FIG. 9(b) and FIG. 9(c) illustrate the conventional methods, respectively, which are generally used to permit the coil 5 to be mounted around the outer circumference of the lens holder 4.
In the first coil winding method shown in FIG. 9(b), the lens holder 4 includes spacer portions 4a, 4b previously formed on the outer circumferential surface, the spacer portions 4a, 4b serving as the protrusions that are used to position the coil 5 in the vertical direction. Using the spacer portions 4a, 4b as reference, the coil 5 will then be wound in the circumferential direction of the lens holder 4.
It should be noted that the spacer portions 4a, 4b are provided so that they can be flush with the height of the coil 5 in the vertical direction. In the first coil winding method, however, there is a problem in that it is difficult to wind the coil neatly because of the coil diameter and the adverse effect of the size tolerance of the lens holder 4 on the winding width adjustment.
On the other hand, the second coil winding method shown in FIG. 9(c) is directed toward solving the problem associated with the first coil winding method, in which a winding width adjusting means 10 is inserted into the inner side of the spacer portion 4a and the coil 5 is then wound by using the winding width adjusting means 10 as reference.
Although the second method can solve the problem associated with the first method, there is another problem in that a gap will arise between the spacer portion 4a and the wound coil 5 after the winding width adjusting means 10 has been removed as shown in FIG. 9(d). The presence of such gap will cause the coil 5 wound on the lens holder 4 to rattle or become unsteady as indicated by an arrow 11.
The lens driving device 1 is a delicate device for which it is not easy to mount the device with the high precision and to ensure that the device will be maintained to be mounted stably. In order to solve this problem, therefore, there is a proposal that is intended for ensuring that the device will be positioned accurately and will be maintained stably in that position (for example, Patent Document 1).
It should be noted, however, that the above proposal is not intended for providing the possibility for making it easier to wind the coil neatly around the lens holder and for preventing the wound coil from rattling or becoming unsteady.